When self-assembled monolayer (SAM) by 11-Mercaptoundecanoic acid (MUA) and AuNPs were used to modify the
sensor surface and to amplify the signals, quartz microbalance (QCM) immunosensors showed good detection sensitivity,
i.e., detection limit as low as 102 CFU/mL for E. coli in less than 30 min could be achieved. Though the modification process
on the sensor surface still involved several steps, the immobilization process could be readily replaced by easy regeneration of
antibodies immobilized sensor surface. Fe2O3/Au core/shell nanoparticles were fabricated to improve surface functionality and
reduce surface oxidizationof iron oxide. By using SAMs with MUA and functionalized Fe2O3/Au nanoparticles, an improved
QCM biosensor with detection limit of 102 CFU/mL for bacteria detection could be obtained. The detection sensitivity of QCM
biosensor with Fe2O3/Au nanoparticles can potentially be improved after further optimizing of Fe2O3/Au nanoparticles.